hostip: move code to resolve IP address literals to Curl_resolv

The code was duplicated in the various resolver backends.

Also, it was called after the call to `Curl_ipvalid`, which matters in
case of `CURLRES_IPV4` when called from `connect.c:bindlocal`. This
caused test 1048 to fail on classic MinGW.

The code ignores `conn->ip_version` as done previously in the
individual resolver backends.

Move the call to the `resolver_start` callback up to appease test 655,
which wants it to be called also for literal addresses.

Closes https://github.com/curl/curl/pull/4798

lib/asyn-ares.c

@@ -626,26 +626,11 @@ Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
 {
   char *bufp;
   struct Curl_easy *data = conn->data;
-  struct in_addr in;
   int family = PF_INET;
-#ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
-  struct in6_addr in6;
-#endif /* CURLRES_IPV6 */
 
   *waitp = 0; /* default to synchronous response */
 
-  /* First check if this is an IPv4 address string */
-  if(Curl_inet_pton(AF_INET, hostname, &in) > 0) {
-    /* This is a dotted IP address 123.123.123.123-style */
-    return Curl_ip2addr(AF_INET, &in, hostname, port);
-  }
-
 #ifdef ENABLE_IPV6 /* CURLRES_IPV6 */
-  /* Otherwise, check if this is an IPv6 address string */
-  if(Curl_inet_pton (AF_INET6, hostname, &in6) > 0)
-    /* This must be an IPv6 address literal.  */
-    return Curl_ip2addr(AF_INET6, &in6, hostname, port);
-
   switch(conn->ip_version) {
   default:
 #if ARES_VERSION >= 0x010601

lib/asyn-thread.c

@@ -71,7 +71,6 @@
 #include "strerror.h"
 #include "url.h"
 #include "multiif.h"
-#include "inet_pton.h"
 #include "inet_ntop.h"
 #include "curl_threads.h"
 #include "connect.h"
@@ -692,26 +691,11 @@ Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
                                          int port,
                                          int *waitp)
 {
-  struct in_addr in;
   struct Curl_easy *data = conn->data;
   struct resdata *reslv = (struct resdata *)data->state.resolver;
 
   *waitp = 0; /* default to synchronous response */
 
-#ifdef ENABLE_IPV6
-  {
-    struct in6_addr in6;
-    /* check if this is an IPv6 address string */
-    if(Curl_inet_pton(AF_INET6, hostname, &in6) > 0)
-      /* This is an IPv6 address literal */
-      return Curl_ip2addr(AF_INET6, &in6, hostname, port);
-  }
-#endif /* ENABLE_IPV6 */
-
-  if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
-    /* This is a dotted IP address 123.123.123.123-style */
-    return Curl_ip2addr(AF_INET, &in, hostname, port);
-
   reslv->start = Curl_now();
 
   /* fire up a new resolver thread! */
@@ -743,25 +727,6 @@ Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
 
   *waitp = 0; /* default to synchronous response */
 
-#ifndef USE_RESOLVE_ON_IPS
-  {
-    struct in_addr in;
-    /* First check if this is an IPv4 address string */
-    if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
-      /* This is a dotted IP address 123.123.123.123-style */
-      return Curl_ip2addr(AF_INET, &in, hostname, port);
-  }
-#ifdef ENABLE_IPV6
-  {
-    struct in6_addr in6;
-    /* check if this is an IPv6 address string */
-    if(Curl_inet_pton(AF_INET6, hostname, &in6) > 0)
-      /* This is an IPv6 address literal */
-      return Curl_ip2addr(AF_INET6, &in6, hostname, port);
-  }
-#endif /* ENABLE_IPV6 */
-#endif /* !USE_RESOLVE_ON_IPS */
-
 #ifdef CURLRES_IPV6
   /*
    * Check if a limited name resolve has been requested.

lib/hostip.c

@@ -59,6 +59,7 @@
 #include "strerror.h"
 #include "url.h"
 #include "inet_ntop.h"
+#include "inet_pton.h"
 #include "multiif.h"
 #include "doh.h"
 #include "warnless.h"
@@ -512,13 +513,11 @@ int Curl_resolv(struct connectdata *conn,
   if(!dns) {
     /* The entry was not in the cache. Resolve it to IP address */
 
-    Curl_addrinfo *addr;
+    Curl_addrinfo *addr = NULL;
     int respwait = 0;
-
+#ifndef USE_RESOLVE_ON_IPS
-    /* Check what IP specifics the app has requested and if we can provide it.
+    struct in_addr in;
-     * If not, bail out. */
+#endif
-    if(!Curl_ipvalid(conn))
-      return CURLRESOLV_ERROR;
 
     /* notify the resolver start callback */
     if(data->set.resolver_start) {
@@ -531,13 +530,35 @@ int Curl_resolv(struct connectdata *conn,
         return CURLRESOLV_ERROR;
     }
 
+#ifndef USE_RESOLVE_ON_IPS
+    /* First check if this is an IPv4 address string */
+    if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
+      /* This is a dotted IP address 123.123.123.123-style */
+      addr = Curl_ip2addr(AF_INET, &in, hostname, port);
+#ifdef ENABLE_IPV6
+    if(!addr) {
+      struct in6_addr in6;
+      /* check if this is an IPv6 address string */
+      if(Curl_inet_pton(AF_INET6, hostname, &in6) > 0)
+        /* This is an IPv6 address literal */
+        addr = Curl_ip2addr(AF_INET6, &in6, hostname, port);
+    }
+#endif /* ENABLE_IPV6 */
+#endif /* !USE_RESOLVE_ON_IPS */
+
+    if(!addr) {
+      /* Check what IP specifics the app has requested and if we can provide
+       * it. If not, bail out. */
+      if(!Curl_ipvalid(conn))
+        return CURLRESOLV_ERROR;
+
       if(allowDOH && data->set.doh) {
         addr = Curl_doh(conn, hostname, port, &respwait);
       }
       else {
         /* If Curl_getaddrinfo() returns NULL, 'respwait' might be set to a
-         non-zero value indicating that we need to wait for the response to the
+           non-zero value indicating that we need to wait for the response to
-         resolve call */
+           the resolve call */
         addr = Curl_getaddrinfo(conn,
 #ifdef DEBUGBUILD
                                 (data->set.str[STRING_DEVICE]
@@ -546,6 +567,7 @@ int Curl_resolv(struct connectdata *conn,
 #endif
                                 hostname, port, &respwait);
       }
+    }
     if(!addr) {
       if(respwait) {
         /* the response to our resolve call will come asynchronously at

lib/hostip4.c

@@ -52,7 +52,6 @@
 #include "share.h"
 #include "strerror.h"
 #include "url.h"
-#include "inet_pton.h"
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
 #include "curl_memory.h"
@@ -128,25 +127,9 @@ Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
 #endif
   Curl_addrinfo *ai = NULL;
   struct hostent *h = NULL;
-  struct in_addr in;
   struct hostent *buf = NULL;
 
-#ifdef ENABLE_IPV6
-  {
-    struct in6_addr in6;
-    /* check if this is an IPv6 address string */
-    if(Curl_inet_pton(AF_INET6, hostname, &in6) > 0)
-      /* This is an IPv6 address literal */
-      return Curl_ip2addr(AF_INET6, &in6, hostname, port);
-  }
-#endif /* ENABLE_IPV6 */
-
-  if(Curl_inet_pton(AF_INET, hostname, &in) > 0)
-    /* This is a dotted IP address 123.123.123.123-style */
-    return Curl_ip2addr(AF_INET, &in, hostname, port);
-
 #if defined(HAVE_GETADDRINFO_THREADSAFE)
-  else {
   struct addrinfo hints;
   char sbuf[12];
   char *sbufptr = NULL;
@@ -167,7 +150,6 @@ Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
    * Since there are three different versions of it, the following code is
    * somewhat #ifdef-ridden.
    */
-  else {
   int h_errnop;
 
   buf = calloc(1, CURL_HOSTENT_SIZE);
@@ -301,10 +283,8 @@ Curl_addrinfo *Curl_ipv4_resolve_r(const char *hostname,
    * getaddrinfo() nor gethostbyname_r() function or for which
    * gethostbyname() is the preferred one.
    */
-  else {
   h = gethostbyname((void *)hostname);
 #endif /* HAVE_GETADDRINFO_THREADSAFE || HAVE_GETHOSTBYNAME_R */
-  }
 
   if(h) {
     ai = Curl_he2ai(h, port);